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BIOL 2321 - Cell Bio Lab > ELISA > Flashcards

Flashcards in ELISA Deck (27)
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1
Q

What does ELISA stand for?

A

Enzyme Linked Immunosorbent Assay

2
Q

Generally, what is ELISA used for?

A

to detect small amounts of proteins (antibodies or antigens) in a sample

3
Q

What does indirect ELISA detect?

A

Antibodies in serum

4
Q

What does direct ELISA detect?

A

Antigens in serum

5
Q

What type of ELISA did we use in lab?

A

indirect

6
Q

How will the concentration of antibodies be effected after the immune system has been exposed to a virus and has launched a response?

A

the concentration of antibodies will be high

7
Q

How will the concentration of antibodies be effected during an immune response to a virus?

A

the concentration will be high

8
Q

How will the concentration of antibodies be effected after the immune system has recovered from a virus?

A

the concentration will be low

9
Q

Give examples of the kind of viruses or infections can ELISA be used for

A
HIV
Flus
West Nile Virus
Small Pox
Lyme disease
10
Q

What are 3 advantages of using ELISA for testing?

A

it is cheap, highly sensitive, and produces quick results

11
Q

What are antigens?

A

usually proteins or polysaccharides on the surfaces of invasive cells and viruses that trigger an immune response in the host body

12
Q

How do antibodies bind to antigens?

A

with great specificity like a lock and key

13
Q

What virus or infection did we simulate in lab?

A

West Nile Virus

14
Q

What is the first step of indirect ELISA?

A

purified antigens of the infectious agent are loaded into plastic microtiter wells

15
Q

What happens when the antigens are loaded into the microtiter wells?

A

the antigens bind to the bottom of the wells via hydrophobic interactions

16
Q

How many washes are there in indirect ELISA? What are the purposes of washing?

A

3 washes

Each wash rinses away material that has not bound to the wells or the antigens or the primary antibodies so that the substance in the wells is pure

17
Q

After the first wash, what would be rinsed away?

A

any unbound material that the antigens may have been loaded with

18
Q

What is added to the microtiter wells after the antigens have been washed?

A

the patient’s blood serum

19
Q

Once added, what will happen if the patient’s blood contains antibodies for the antigens in the wells?

A

the antibodies from the patient’s blood will recognize the antigens and bind tightly to them at the bottom of the well

20
Q

What is the purpose of the second wash in indirect ELISA?

A

the second wash will remove any antibodies from the patient’s blood that did not bind to the antigens - this helps in the accuracy of the results

21
Q

What is added to the microtiter after the second wash?

A

secondary antibodies (recognize human antibodies as an antigen) are added to the microtiter and bind to the primary antibodies that are already bound to the antigens

22
Q

What is the purpose of adding the secondary antibodies?

A

they contain a conjugate enzyme which can facilitate the colour change of the chromagen substrate when it is added - this allows us to visualize the results of the ELISA

23
Q

What is the purpose of the third wash?

A

it will rinse off any secondary antibodies that did not bind to the human antibody-antigen complex

this will allow for accuracy in the results so that there’s no conjugate enzymes to change colours where there is no human antibodies

24
Q

What is the last thing added to the microtiter?

A

chromagen substrate

25
Q

What happens to the chromagen substrate if there are antibodies present?

A

if the secondary antibody bound to a human primary antibody, the conjugate enzyme on the secondary enzyme facilitates the colour change of the chromagen substrate from clear to purple which gives us a positive result for infection

26
Q

What does it mean if the chromogen substrate changes to dark purple?

A

there are lots of antibodies present and the patient is likely in the midst of fighting off the infection = they have an infection

positive for the infection

27
Q

What does it mean if the chromogen substrate changes to light purple?

A

a weak positive

the patient is likely at the beginning or end of the infection and there is a low concentration of antibodies